Composite panel containing lauan or other moisture-carrying or moisture-absorbing material using adhesion promoter

ABSTRACT

A composite panel includes a mold surface, a layer of gel coat applied to the mold surface, a wet laminate containing a resin applied to the layer of gel coat, a substrate of lauan or another moisture-carrying or moisture-absorbing material placed on the wet laminate, and a layer of a bonding promoter provided at the interface of the substrate with the wet laminate, additional to any amount of promoter(s) present in the resin of the wet laminate. Without previously curing or drying the layer consisting essentially of the bonding promoter in the solvent, each of the wet laminate, the bonding promoter, and the gel coat are simultaneously cured.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No.15/588,082, filed May 5, 2017, which claims priority to U.S. ProvisionalPatent Application No. 62/345,946, filed Jun. 6, 2016, the disclosuresof which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a composite panel. More specifically,this disclosure relates to a composite panel containing lauan or anothermoisture-carrying or moisture-absorbing material using an adhesionpromoter.

BACKGROUND

This invention relates to an improved method of manufacturing acomposite panel using lauan and the panel made using the method (whilethe method is applicable to panels using lauan or othermoisture-carrying or moisture-absorbing materials, reference will forthe most part be limited to lauan, in the interest of conciseness). Inthe conventional production of composite panels with lauan, a gel coatlayer is first laid down on a mold, followed by a layer of resin andglass fibers, thus forming a wet laminate. A layer of lauan is thenapplied directly to the wet laminate. The resin contains one or morepromoters, and depending on the resin used, peroxide may also be addedto the resin just before it is introduced into the mold. The peroxideacts as a cure initiator by reacting with the promoter and causing theresin to polymerize and harden. It additionally results in the resinbonding to the lauan, forming a flat, hard composite sheet.

Sometimes the lauan, although apparently exhibiting acceptable adhesion,does not form a strong bond to the cured laminate, resulting in a panelthat can undergo delamination. The present inventor has determined thatthis problem is more likely to occur with increased water content of thelauan. The inventor thus believes that the problem is due to excessmoisture in the lauan, and that this water inhibits the cure of theresin at the interface by interfering with the reaction between peroxideand promoter, resulting in poor adhesion to the lauan. Unfortunately,attempting to solve this problem by simply adding extra promoter to theresin is not practical. The extra promoter changes the speed at whichpolymerization occurs, thus causing timing problems in the productionprocess, as well as increasing consumption of the promoter.

One might attempt to manage this problem by inspecting all lauan formoisture content before using it. This reduces the likelihood ofproducing panels that are subject to delamination, but requires extralabor for the inspection, as well as storing the high-moisture lauan andreturning it to the vendor. Similarly, attempting to dry the too-moistpieces of lauan before use would require still more labor, as well asrequiring the availability of drying equipment and use of energy for thedrying process.

SUMMARY

The present method involves applying promoter at the resin-substrate(e.g., lauan) interface. This is preferably done by spraying thepromoter onto the top surface of the resin before the lauan is placed ontop, but it may instead be done by spraying or rolling the promoter ontothe lauan itself. Most generally, it may be done by providing promoterat the resin-lauan interface in any manner that may be convenient(provided that little to no extra promoter is added to the rest of theresin layer). The present inventor has found that doing this may reducethe likelihood of delamination even with lauan that happens to have ahigh moisture content that would otherwise be problematic, and in fact,may enable one to reduce or even practically eliminate the problemrather than just managing it.

According to certain embodiments, a method of manufacturing a lauancomposite panel, and the panel so made, are provided. A layer of gelcoat is formed on a mold surface, a wet laminate containing a resin isapplied to the layer of gel coat on the mold surface, a lauan or othersubstrate is placed on the wet laminate, and the combination is cured.Prior to curing, there is provided a layer of a bonding promoter at theinterface of the lauan substrate with the wet laminate, additional toany amount of promoter(s) present in the resin of the wet laminate.

The features and advantages herein will become more apparent from thedetailed description set forth below when taken in conjunction with thedrawings, in which like reference numbers indicate identical orfunctionally similar elements.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “include” and “comprise,” as well as derivativesthereof, mean inclusion without limitation. The term “or” is inclusive,meaning and/or. The phrase “associated with,” as well as derivativesthereof, means to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, have a relationshipto or with, or the like. The phrase “at least one of,” when used with alist of items, means that different combinations of one or more of thelisted items may be used, and only one item in the list may be needed.For example, “at least one of: A, B, and C” includes any of thefollowing combinations: A, B, C, A and B, A and C, B and C, and A and Band C.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 is an illustration of one preferred embodiment of a methodaccording to the present invention;

FIG. 2 is an illustration of a second preferred embodiment;

FIG. 3 is an illustration of a third preferred embodiment;

FIG. 4 is an illustration of a panel made according to the process ofFIG. 1, 2 or 3; and

FIG. 5 is a cross-sectional view of the panel shown in FIG. 4.

DETAILED DESCRIPTION

FIGS. 1 through 5, discussed below, and the various embodiments used todescribe the principles of the present disclosure are by way ofillustration only and should not be construed in any way to limit thescope of the disclosure. Those skilled in the art will understand thatthe principles of the present disclosure may be implemented in anysuitably arranged method or device.

As stated above, the conventional method of manufacturing a lauancomposite panel involves forming a layer of gel coat on the surface of amold of at least the size of the panel to be made. On the gel coat isformed a wet laminate, of a resin containing a promoter and possiblyperoxide, and fiber glass fibers as a reinforcement. The wet laminatemay be sprayed onto the gel coat, such as by spraying the resin onto thegel coat, followed by (or mixed with) the glass fibers, and then rollingthe surface of the layer to achieve evenness. A sheet of lauan is thenpositioned on the wet laminate; for a typical panel, a number of piecesof lauan are actually used, and are placed abutting each other to coverthe wet laminate.

The wet laminate is then cured. This may be done by encasing the entiremold in a vacuum bag, exposing the mold with the gel coat and otherlayers on it to a vacuum, and applying heat. Alternatively, heat alonemay be used.

FIG. 1 illustrates one preferred embodiment of a method according to thepresent disclosure. A horizontal flat mold is provided, and is coatedwith a gel coat layer (not illustrated). A first spray head, showntoward the right in that Figure, is used to spray the mix of resin andglass fibers onto the gel coat. As in a conventional method, this mixmay also include a promoter in an amount sufficient to achieve properpolymerization of the resin during curing, but should not contain somuch as to change the curing time.

A second spray head sprays promoter onto the wet laminate, as shown tothe left of the first spray head. This promoter may be the same as isincluded in the wet laminate itself, but that need not be the case, asdiscussed below. The wet laminate, coated with the promoter by thesecond spraying head, is then covered with the required number of piecesof lauan. (To be more precise, the wet laminate may not be exactly andcompletely covered by the lauan, as a peripheral portion of the laminatemay remain uncovered.)

When the entire mold has been provided with each of the mentionedlayers, it is enclosed in a vacuum bag (not illustrated), and the resinof the wet laminate is cured under vacuum and heat. Alternatively, othertechniques of curing may be used. The finished panel is then releasedfrom the mold and cut to size if necessary.

An example of a panel manufactured in this fashion is shown in FIGS. 4and 5. As may be seen, one surface of the panel is formed by the lauansubstrate, which is bonded to the fiberglass laminate. The other side ofthe laminate is bonded to the high-gloss gel coat. In both Figures theinterface layer between the lauan substrate and the fiberglass laminateis labeled, and the thin layer of adhesion promoter is illustrated aswell (see FIG. 4).

While reference has been made above simply to a promoter being appliedto the lauan-laminate interface, in practice of course what is appliedis a solution of the promoter(s), so that what is applied includes oneor more promoters, a solvent, and if needed a material to dilute theconcentration of the promoter(s) to the desired value. It is believedthat the following may be used as suitable promoters, although it shouldbe understood that neither this list nor the following list of solventsis intended to be exhaustive:

-   -   Promotors, including but not limited to:        -   Copper salts        -   Manganese salts        -   Iron salts        -   Cobalt salts        -   Amine accelerators        -   Dimethyl aniline        -   Dimethyl-p-toluidine        -   Vanadium accelerators        -   Vanadium monobutyl dihydrophosphite        -   2,4-Pentanedione        -   N,N-Diethylacetoacetamide    -   Solvents, including but not limited to:        -   Mineral spirits        -   Methyl ethyl ketone        -   Styrene        -   Acetone        -   Methyl methacrylate        -   Xylene

The mixture ratio of solvent to promoter can range, for example, from10:1 to 1000:1, or more particularly from 20:1 to 800:1, or from 50:1 to500:1, or from 100:1 to 300:1.

One preferred embodiment applies 1% cobalt-acetone drying solution asthe solvent-promoter mixture, applied to the lauan with target coverageof 3 grams/square foot (about 32 grams/square meter). Another exampleuses cobalt with mineral spirits. Other mixtures, as stated, may beused.

Also, the promoter used in the solvent-promoter mixture may be one (ormore) also used in the resin, or instead may include one or more notused in the resin.

While the embodiment described above with reference to FIG. 1 isparticularly preferred due to the ease of manufacturing the productusing that embodiment, other embodiments are also contemplated. A secondexample of a preferred embodiment of the method is illustrated in FIG.2. In that embodiment, instead of spraying the promoter onto the wetlaminate, the promoter is sprayed onto one surface of the lauan shortlybefore the lauan is positioned on the wet laminate. Each sheet of lauan,after being sprayed with the proper amount of promoter solution, isturned over and placed with the sprayed surface in contact with the wetlaminate.

Another example is illustrated in FIG. 3, in which the promoter solutionis again applied to the lauan rather than to the wet laminate, but theapplication is done using a roller rather than a spray head. Similarly,to FIG. 2, after application of the promoter, each sheet of lauan isinverted and positioned with the coated surface in contact with the wetlaminate. In both variants (FIGS. 2 and 3), the rest of the procedure isthe same as in that illustrated in FIG. 1.

Additional variations in the method are within the broad scope of thepresent invention. For example, while only application by spraying or byuse of a roller have been mentioned, any other mechanized or manualmethod of application of the promoter that may be found convenient maybe used. Also, an individual mold may be used for each panel, or acontinuous mold may be used. Again, the mold may be moved past each workstation in turn for application of the gel coat, of the wet laminate, ofthe promoter and of the lauan, and then for the curing, or alternativelythe mold may be stationary.

Results obtained have been good, based on testing including forregularity of product surface or surface profile, and mechanical, suchas flex, tensile and, block pull tests, with moisture contents from Oto19% (and, particularly, with high moisture content, of e.g., 13-18% andespecially 14-17%; all % are weight-%). Moreover, the inventor has foundthat advantageous results may be obtained regardless of whether thelauan used is sanded or not, and for different thicknesses of lauan.Additionally, the method may yield advantageous results whether theresin used contains a filler, such as mica, or not. Further, it isbelieved that this method may produce satisfactory results with anymoisture content up to the level at which the lauan would beunacceptable based on other criteria.

Furthermore, while this method has been described with particularrelation to the manufacture of a panel having a lauan substrate bondedto a resin-fiberglass layer that is bonded to a gel coat, the method isapplicable as well to the manufacture of other types of article in whichit is desired to bond lauan or a similar material to a resin layer,whether containing glass fibers or not. The method is also applicable toother woods than lauan, such as plywood, and to other substrates thatmay carry or absorb moisture.

While various example embodiments of the present invention have beendescribed above, it should be understood that they have been presentedby way of example, and not limitation. It will be apparent to personsskilled in the relevant art(s) that various changes in form and detailcan be made therein. Thus, the present invention should not be limitedby any of the above described example embodiments, but should be definedonly in accordance with the following claims and their equivalents.

Further, the purpose of the following Abstract is to enable the U.S.Patent and Trademark Office and the public generally, and especially thescientists, engineers and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. The Abstract is not intended to be limiting as to thescope of the example embodiments presented herein in any way. It is alsoto be understood that the procedures recited in the claims need not beperformed in the order presented.

Although the present disclosure has been described with variousembodiments, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as falling within the scope of theclaims.

The present disclosure should not be read as implying that anyparticular element, step, or function is an essential element, step, orfunction that must be included in the scope of the claims. Moreover, theclaims are not intended to invoke 35 U.S.C. § 112(f) unless the exactwords “means for” are followed by a participle.

What is claimed is:
 1. A composite panel, comprising: a mold surface; alayer of gel coat applied to the mold surface; a wet laminate applied tothe layer of the gel coat, the wet laminate comprising a resin; asubstrate of lauan or other moisture-carrying or moisture-absorbingmaterial placed on the wet laminate; a layer consisting essentially of abonding promoter in a solvent provided at an interface of the substratewith the wet laminate, additional to any amount of promoter(s) presentin the resin of the wet laminate, wherein, without previously curing ordrying the layer consisting essentially of the bonding promoter in thesolvent, each of the wet laminate, the bonding promoter, and the gelcoat are simultaneously cured.
 2. The composite panel of claim 1,wherein the layer consisting essentially of the bonding promoter in thesolvent is applied to an exposed surface of the wet laminate.
 3. Thecomposite panel of claim 2, wherein the layer consisting essentially ofthe bonding promoter in the solvent is applied to the exposed surface ofthe wet laminate before the substrate is placed on the wet laminate. 4.The composite panel of claim 2, wherein the layer consisting essentiallyof the bonding promoter in the solvent is sprayed onto the exposedsurface of the wet laminate.
 5. The composite panel of claim 4, whereinthe layer consisting essentially of the bonding promoter in the solventis sprayed onto the exposed surface of the wet laminate before thesubstrate is placed on the wet laminate.
 6. The composite panel of claim1, wherein the layer consisting essentially of the bonding promoter inthe solvent is applied to an exposed surface of the substrate.
 7. Thecomposite panel of claim 6, wherein the layer consisting essentially ofthe bonding promoter in the solvent is applied to the exposed surface ofthe substrate before the substrate is placed on the wet laminate.
 8. Thecomposite panel of claim 6, wherein the layer consisting essentially ofthe bonding promoter in the solvent is sprayed onto the exposed surfaceof the substrate.
 9. The composite panel of claim 6, wherein the layerconsisting essentially of the bonding promoter in the solvent is rolledonto the exposed surface of the substrate.
 10. The composite panel ofclaim 1, wherein the layer consisting essentially of the bondingpromoter in the solvent is provided by applying a solution of thepromoter in the solvent in a concentration of the solvent to thepromoter in a range of 10:1 to 1000:1, inclusive.
 11. The compositepanel of claim 10, wherein the layer consisting essentially of thebonding promoter in the solvent is provided by applying a solution of apromoter selected from the group consisting of copper salts, iron salts,and cobalt salts.
 12. The composite panel of claim 10, wherein the layerconsisting essentially of the bonding promoter in the solvent isprovided by applying a solution of a promoter selected from the groupconsisting of amine accelerators, dimethyl aniline,dimethyl-p-toluidine, vanadium accelerators, vanadium monobutyldihydrophosphite, 2,4-pentanedione, and N,N-diethylacetoacetamide. 13.The composite panel of claim 10, wherein the layer consistingessentially of the bonding promoter in the solvent is provided byapplying a solution containing a material selected from the groupconsisting of mineral spirits, methyl ethyl ketone, styrene, acetone,methyl methacrylate and xylene as a solvent.
 14. The composite panel ofclaim 1, wherein the resin further includes glass fibers.
 15. Thecomposite panel of claim 1, wherein the substrate is plywood.
 16. Thecomposite panel of claim 1, wherein the substrate is a wood other thanlauan or plywood.
 17. The composite panel of claim 1, wherein thesubstrate has a moisture content of up to 19 weight %.
 18. The compositepanel of claim 1, wherein the substrate has a moisture content of 13-18weight %.
 19. The composite panel of claim 1, wherein the substrate hasa moisture content of 14-17 weight %.